1. Field of the Invention
The present invention relates to a rocker arm installed module which is used in an engine valve opening and closing mechanism and in which a pivot, a rocker arm and a cam shaft are installed in a housing.
2. Description of the Related Art
A valve opening and closing mechanism for use in a reciprocal engine of a vehicle or the like is constructed so as to execute suction and exhaust of air in combustion of engine by opening and closing an engine valve for suction and exhaust of air by receiving a rotation of a cam in a cam shaft and rocking a rocker arm. In an overhead cam (OHC) type engine, an end of the rocker arm is in engagement with the top of a pivot which forms a rocking support point while the other end thereof is in engagement with the top of a stem front end portion of the engine valve. In the rocker arm, a roller supported between a pair of supporting walls is kept in contact with the cam located thereabove. When the engine is actuated, the rocker arm rocks such that it is sandwiched among the cam, the pivot and the engine valve so as to open and close the engine valve.
In the above-described conventional valve opening and closing mechanism, the pivot, the rocker arm and the cam shaft are installed directly onto a cylinder head of the engine. Thus, these components have never been formed into a module by installing them separately from the cylinder head up to now. Further, if no engine valve exists below the rocker arm when the rocker arm is installed, it might drop off because its posture is not stabilized.
In the meantime, patent document 1 has disclosed an internal combustion engine in which a guide wall capable of receiving the bottom face of a push rod when the cam follower is removed is formed on the cylinder head. However, even in the patent document 1, any device for formation into a module or any device for preventing the rocker arm from dropping off has not been achieved like the above-described conventional valve opening and closing mechanism.
Patent document 1: JP61-279710 Unexamined Patent Publication (Kokai)